the pulsating noise may be the water meter operating. The noise can be caused by the sprinkler system having too many heads running at one time, creating a high flow rate.

: I have a new house that a sprinkler system was installed in.: When the sprinklers run there is a pulsating noise. The sprinkler installer: has disapeared and I am trying to find the cause. I think it has to do with pipe sizes.: It goes from 3/4 inch to 1 inch copper (Small size to large) fron the source. (Copper): Could this reverse sizing situation cause a noise ? If so is there a baffle or something: that could be installed rather than re-piping the system ?